Fuse



Elank 229 1929. 1,700,080

.sANDwi FUE E Original Flec. une l5 1921 t A, I e

'f-f. l' l l.

ATTORNEY T' 0,6. i q. l i922@ agree/f .1 i. ,a am n il i My inventionrelates to fuses and particularly to refillable cartridge fuses.

@ne object of my invention is to provide a reillalole and renewable fusemechanism wherein the contact surfaces which clamp the fuse ends areprevented from becoming oii dized by reason of repeated fuse blowings.

Another object of my invention is to provide a fuse mechanism havingvented fusesupporting members wherein the fuse member supported therebyis prevented from accidently covering the vent and interfering` with theproper escape of the gases.

Another object of the invention is to provide a fuseesupporting elementhaving the alcove characteristics that may be manufactured as cheaply aselements now employed and that may be applied to standard fuses withoutnecessitating changes therein.

rlh'ese and other objects, that will be made apparent throughout thefurther description of the invention, are attained by means of theapparatus hereinafter described and illustrated in the accompanyingdrawings, wherein:

Figure 1 is a longitudinal section through a fuse embodying myinvention;

Figs. 2 and 3 are perspective views of the clamping disc and thesupporting disc, respectively, shown in Fig. 1; f

Fig. 4 is a front elevation of the closure or cap member, shown in Fig.1

Fig. 5 is a perspectivel view of the fuse shown in Fie'. 1;

Fig. 6 is a side elevation of the modified form of fuse, showing one endthereof in longitudinal section;

Fig. 7 is a perspective view of a modified 3, form of fuse-supportingdisc shown in Fig.

8; and

Fig. 8 is a side elevation of another modied form of fuse, showing oneend in longitudinal section.

In my co-pending application, Serial No. 308,686, filed July 5, 1919, Ihave disclosed a fuse construction having vented fuse-supporting discsand vented clamping discs between which the terminals of a fusibleelement are clamped. The gases of combustion resulting from the ruptureof the fusible, element escape from the casing through the vents in thesupporting discs and pass through the space between the supportingldiscs and the clamping discs to the atmosphere rio. s'f'i. Renewed .Tune25j,

""il/v hen a fuse blows, the adjacent surfaces which are unprotected bythe yfuse element become coated .with particles of the blown fuse, andwhen a fnse element is renewed, the ends thereof do not cover 'the enactplace occupied by the rmer fuse element, and, therefore, parts of thecoated adjacent surfaces clamp the fuse ends and tend to keep thecontact surfaces previously covered and protected by the blown fuse awayfrom the fuse ends. Because of this condition, two or three blowings ofthe fuse elements results in the contact surfaces, becoming entirelycoated with oxides, solder and foreign substances which prevent a goodconductive contact of the fuse element with the clamping members. f Asthe vents of the clamping disc generally consist-of a plurality of smallperforations of 'a definite size and number, depending upon thecapaeityof the fuse and the inten sity of the explosion, it is necessarythat all should function in order that t-he gases may be dischargedatproper velocity to prevent bursting of the fuse casing and to ensureproper pressure, as determined, by test, to be necessary to quicklyextinguish the arc incident to the explosion.

As heretofore constructed, clamping discs have been provided with flatsurfaces, and it frequently occurs that the flat terminal of Y the fusecovers one or more of theperforations or vents and prevents properescape of the gases. Under such conditions, the pressure within the fuseis liable to cause the casing to burst.

The conditions above-referred-to are entirely eliminated by myinvention, which' consists, primarily, in providing ,the clamping discor member with a clamping seat that is spacedifrom the main ventedcooling surface of the member and which supports the fuse terminal inspaced relation with respect to the said surface. The fuse terminalcannot, under any condition, close the vents.

The greatest dimension of the clamping seat is smaller than the minimumdimension of the fuse terminal and, therefore, is completely covered bythe terminalwhich protects the seat from contact withthe gases ofcombustion and the fusible metal carried thereby.

When a blown fuse is removed, the clamping surface is clean and readyfor proper conductive contact with the new fuse. The

supporting discs may also be provided with a similar raised or embossedclamping surface.

Referring to the drawings and particularly to' Figs. land 4, the fusemechanism lincludes an insulating cylindrical shell or I or cap member13 is screwed upon the ferrule 11 and serves to close the ends of tli/ecasing. Each cap 13 is provided with a countersunk chamber 14, in whicha disc 15, preferably made of fullerboard, is loosely disposed, whichserves as a baffle for directing the gases, resulting from the blowingof va fuse, to the outer ends of a plurality of radially disposedgrooves 1G that are provided in the bottom of the countersunk chamber 14and which lead from the edge of the chamber toa central orifice 17.

The fusible member 18, illustrated in Figs. 1 and 5, comprises a flatstrip made of readily fusible metal and is cut away at its edges so asto provide relatively narrow sections 19 for'v the purpose of localizingthe point of Arupture of the fuse. The, fusible member 18 is supportedwithin the casing by means of supporting or centering discs 21 that areprovided, on one side, with a plurality of lugs 22 distributed about thecenter of the disc at equal distances therefrom. vThe lugs 22 fit in theends of the ferrules 11 and serve to center the dise with respect to theeasing. f

The disc is cutv awayat one side, as at 23, for the purpose ofprovidingthe vent 24,

' through which the fiat end or terminal 25 of the fusible member 18extends. The fusible members are usually furnished in flat strips, andthe ends or terminals thereof are bent at substantially right angles tothe body of the fuse, as illustrated in Fig. 1.

As shown in Figs. 1 and 3, the supporting` dise 21 is provided with acircular clamping face 26 having a fuse-engaging surface of lessdiameter than the minimum width of the terminal 25. The surface 26 isspaced a short distance from theniain surface of the disc surface andsupports the fuse out of contact therewith.

The fuse is clamped to the supporting disc 21 by means of a clampingdise 27 that is carried by the cap 13 and is rotatable with respectthereto. The disc 27 is provided With a similar clamping face 28, theplane of which is spaced from the main surface 29 of the discL The leastdimension of the clamping surface 28, like that of the disc 21, is lessthan the minimum dimension of the terminal 25 and, therefore, when thesurface 28 is in operative engagement with the fuse 18, the operativeengaging surface is entirely covered by the fuse terminal 25 and isprotected from gases entering the cooling chamber between the supportingdisc 21 and the clamping disc 27 through the vent 24.

The clamping disc 27 is provided with a plurality of perforations 31that are equally spaced about the circular clamping seat 28. rllhenumber and size of these perforations is determined by the capacity ofthe fuse and the intensity of the explosion thereof, the purpose beingto permit the escape of gas at a velocity that will prevent theexplosion of the casing and, at the same time, maintain the pressurewithin the casing necessary to instantaneously extinguish thc arc. f

rlhe perforations 31 are so positioned that they discharge into thecounter-sunk chamber 14. rlhe gases escaping from the perforations inthe clamping dise 27 force the movable disc l5 against the bottom of thecountersunk chamber 14 and are directed thereby through the grooves 16to the discharge opening 17. f

lt will be seen from the foregoing that, regardless of the length of theterminal 25, the perforations 31 cannot be covered thereby under anycondition. Because the clamping seats of the supporting disc 21 and theclamping discv 27 are completely covered by the fuse terminals, they areprotected from the gases passing between the said discs, andconsequently, are free from the usual deposits of fuse metal and thegases of combustion. It will be understood that the clamping seats aretightly drawn into contact with the fusible element and, therefore, thegases cannot creep between the fuse surface and the seats.

When a new fuse is inserted between the clamping surfaces, a properconductive contact is secured. The surfaces are maintained in cleancondition regardless of repeated explosions and do not require cleaningbefore the insertion of a new fuse. I

Referring to Fig. 6, a modified form of closure construction isillustrated, wherein the cap or closure member 32 is provided with a.clamping seat 33 that is spaced from the main interior face 34 of thecap. The easing 37, the ferrule 38 and the supporting disc 39 aresimilaiin every respect to like parts illustrated in Fig. 1, thedifference in the fuse construction residing in the elimination ofthevent Within the cap and the fullerboard dise. In this construction, thegases escape between the threads of the capiand ferrule.

Referring to Fig. 8, a modified form of ferrule and closure isillustrated, wherein the ferrule 41, that is secured to the casing 42,is internally threaded for receiving the clamping disc 43. The dise isprovided with a clamping face 44 that is spaced from the main internalface 45 of the disc. The gases of combustion escape from the coolingcharner eicls oi between I e l isc i8 is of modified construction anducted as illustratV g. The provided with ce l race that is spaced fromthe surface 5i of the disc for the purpievicusly specified. This disc,howis provided with slet 52 that is cut edge thereof for the purpose ofthe fuse 53. The slot is of greater ian the thickness of the fuse and,con- 'equentiy, permits the gases of combustion within the fuse chamber5- to escape from 'ruse chamber f7 'through the slot. rflic disc iscentered within the ferrule lll..

it will be observed that the clamping surfaces in the modifiedconstructions shown in TFigs. 6 and 8, will be maintained in cleancondition in the manner described in connection with the fuseillustrated in ig'. i.. lt is also apparent that the fuse, in the endvented enclosures, can, at no time, close the vents or obstruct theescape of gases there from.

While ll have described and illustrated but three embodiments of myinvention, it will be apparent to those skilled in the art that variouschanges, modifications, substi tutions, additions and omissions may bemade in the apparatus illustrated without departing from the spirit andscope of the invention, as set forth in the appended claims.

ll claim as my invention ':-v

l. lln a renewable fuse, a. casing, a fusible element, and a supportingstructure for the fusible element including a pair of members eachhaving a vented surface exposed to the gases of combustion and provided.with a clamping lseat spaced from the said surface and engaging the saidfusible member.

2. ln a renewable fuse, a. fusible member, a pair `of vented members forsupporting` the fusible member with a portion thereof between them andhaving transverse gas-cooling surfaces and means for holding the fusibleelement in longitudinally spaced relation with respect to each of thesaid surfaces.

3. lln a renewable fuse, a fusible member having a terminal, and a pairof vertical members for supporting the said terminal between them andeach having a p asecoolw ing surface and clamping face spaced om thegas-cooling rface thereof for engagmg p romembers for clamping a fuseelement be` tween them and providing a passage therebetween, each of thesaid members beprovided with centrally disposed seat of less-diameterthan the width of the fuse element, for supporting the fuse element inspaced relation with adjacent surfaces of the said members.

in fuse, a casing, a fusible member, a vented supporting member and avented closure member for the casing, said supporting` and closuremembers each being provided with centrally raised clamping surface forengaging the fusible member and for clamping it between the closuremember and the supporting member.

6. ln a fuse, a casing, a fusible member, a vented supporting membercarried by the casing` and a closure member for the casing, saidsupporting and closure members each having a centrally disposed, flat,raised clamping seat engaging the fusible member and of less diameterthan the width of the fusible member.

7. ln a fuse, a fusible member, a casing member therefor, a pair ofmembers c0- operating with the casing member to provide a chamberstructure having longitudinally spaced, transversely extending,metallic, gas-cooling surfaces in the casing, and means for clamping aportion of said fusible member in longitudinally spaced relation to oneof said cooling surfaces and preventing the impingement of gases againstthe clamping surfaces of the clamping means.

8. ln a cartridge fuse, a detachable end cap, in combination with awasher carried thereby on its inner face, and a rigid circular boss onthe inner face of the washer for male ing Contact with the end of thefuse strip.

In testimony whereof, l have hereunto subscribed my name this 2nd day ofJ une, 1921.

JEROME SANDIN.

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